4. DEVICE DESCRIPTION AND INTENDED USE The Navigo™ system is comprised of two main elements: a standard laptop computer with a digitizer input to record incoming video input (from the ultrasound system), and an electro-magnetic 3D tracking system. The 3D tracking system is connected via USB to the laptop computer, the transmitter is placed beneath the patient's mattress and two sensors are attached,- one to the ultrasound probe (at the base/ non invasive part of the probe) and the other to the patient's back.